During the latter half of 1995, the US wireless telecommunications industry developed assignment guidelines for International Mobile Subscriber Identities (IMSI) in the US. These guidelines were developed in an open industry forum jointly sponsored by the Cellular Telecommunications Industry Association (CTIA) and the Personal Communications Industry Association (PCIA). The result of this development effort was the consensus-approved document titled IMSI Assignment Guidelines and Procedures.
The guidelines call for the formation of an “appropriate industry forum” tasked with various responsibilities associated with the management of the IMSI resource and oversight of IMSI administration. The forum that was formed is the IMSI Oversight Council (IOC). The IOC is further defined in the Annex B of the IMSI Assignment Guidelines and Procedures which includes its scope, mission, responsibilities, participants, organization, operational procedures, and interworking.
The IOC is responsible for the management and administration of International Mobile Subscriber Identities (IMSI) in the United States and maintains compliance with the "IMSI Assignment Guidelines and Procedures" to ensure that it meets the evolving needs of the U.S. wireless telecommunications industry.